This application relates to a method for pillaring a layered silicate, such as kenyaite, with polymeric oxide by using a mixture of swelling agent and pillar precursor.
Layered silicates such as magadiite are layered materials which have structures distinct from zeolite structures such as that of ZSM-5. Layered materials have three-dimensional structures which exhibit their strongest chemical bonding in only two dimensions. In such materials, the stronger chemical bonds are formed in two-dimensional planes and a three-dimensional solid is formed by stacking such planes on top of each other. However, the interactions between the planes are weaker than the chemical bonds holding an individual plane together. The weaker bonds generally arise from interlayer attractions such as Van der Waals forces, electrostatic interactions, and hydrogen bonding. In those situations where the layered structure has electronically neutral sheets interacting with each other solely through Van der Waals forces, a high degree of lubricity is manifested as the planes slide across each other without encountering the energy barriers that arise with strong interlayer bonding. Graphite is an example of such a material. The silicate layers of a number of clay materials are held together by electrostatic attraction mediated by ions located between the layers. In addition, hydrogen bonding interactions can occur directly between complementary sites on adjacent layers, or can be mediated by interlamellar bridging molecules.
U.S. Pat. No. 4,859,648, the entire disclosure of which is expressly incorporated herein by reference, points out that layered oxide materials including layered silicates, such as magadiite and kenyaite, may be intercalated with polymer oxides to provide catalysts suitable for various hydrocarbon conversions.